Method and apparatus for recognition of writing, for remote communication, and for user defined input templates

ABSTRACT

A device including a housing, a writing tip connected to the housing, a writing surface position indicator, a processor in the housing, a memory device in the housing connected to the processor, and a sensor in the housing and cooperative with the writing surface position indicator. The device may be used to record writings and drawings applied to a surface by a user, to transmit that data to a remote device, to download data from remote devices, and to otherwise communicate with remote devices.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from provisional U.S. PatentApplication serial No. 60/076,338, filed Feb. 27, 1998.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable.

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention is directed generally to a method anddevice for recognition of writing and communication with remote devices.

[0005] 2. Description of the Background

[0006] The use of computers for data entry and communication has becomelimiting and inconvenient in some aspects. For example, the use of acomputer keyboard requires repetitive motion that is known to causephysical discomfort and, in some cases, physical injury. In addition,computers are relatively large devices. Even the advent of laptopcomputers has not made data entry and communication easy. One reason isthat a laptop cannot be smaller than a keyboard and, to be efficient, akeyboard must have keys at least as large as a typical user's fingers Asa result, the size of a laptop computer is not foreseen to reducesignificantly in the future. In any event, it is not foreseen to becomesmall enough to be carried by a person with little or no inconvenience.

[0007] To address these problems, some relevant art discloses hand-helddevices for data entry, typically in the form of handwritingrecognition. Many of those devices, however, require a written orsensory grid in order to determine the motion of the device and read thelines drawn by a user. Some devices require special purpose input padsto monitor the writing and drawing of a user. Other devices require thata user only print using special characters in order for handwritingrecognition to work. All of those devices also suffer the inability tomonitor multiple writings by a user on an ordinary piece of paper. Otherdevices allow for multiple writings on an ordinary piece of paper, butdo not compensate for movement of the paper relative to the writinginstrument. Thus, the prior art devices inaccurately recognize thewritings because the user compensates for the movement of the paper, butthe device is not able to determine that user has so compensated.

[0008] As a result, the need exists for a device that provides for easyand convenient data entry and communication, as well as the ability touse any surface and to be able to accurately monitor a user's actions.

BRIEF SUMMARY OF THE INVENTION

[0009] The present invention is directed to a device including ahousing, a writing tip connected to the housing, a writing surfaceposition indicator, a processor in the housing, a memory device in thehousing connected to the processor, and a sensor in the housing andcooperative with the writing surface position indicator. The device maybe used to record writings and drawings applied to the surface by theuser, to transmit that data to a remote device, to download data fromremote devices, and to otherwise communicate with remote devices.

[0010] The present invention is also directed to a device including ahousing, writing tip connected to the housing, a processor in thehousing, and a memory device in the housing connected to the processorhaving stored thereon instructions which when executed by the processorcause the processor to recognize an interface defined by writing on awriting surface.

[0011] The present invention provides the advantage in that it permitsdata entry with a hand-held device which does not require a specialwriting surface. The present invention also provides the advantage thatdata can be entered accurately because the device compensates formovement of the writing surface during the writing process. The presentinvention also provides the advantage that the data can be stored intothe writing instrument itself, rather than having to transmit the datato a remote device. The present invention also provides the advantagethat the device can communicate with remote devices. The presentinvention also provides the advantage that a user can define a personalinterface, which can be stored by the device, to enter data or instructthe device to perform certain commands. These and other advantages andbenefits of the present invention will become apparent from the detaileddescription of the invention hereinbelow.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0012] For the present invention to be clearly understood and readilypracticed, the present invention will be described in conjunction withthe following figures, wherein:

[0013]FIG. 1 is a side plan view of a device constructed in accordancewith the present invention;

[0014]FIG. 2 is a block diagram illustrating components of the device;

[0015]FIG. 3 is a top plan view of the device being used to write on apiece of paper;

[0016]FIG. 4 is a top plan view of the device being used to define apersonal interface on a piece of paper;

[0017]FIG. 5 is a top plan view of the device being used to define analternative personal interface on a piece of paper;

[0018]FIG. 6 is a side plan view of the device in a base; and

[0019]FIG. 7 is a side plan view of an alternative embodiment of thedevice formed as a ring on a user's finger.

DETAILED DESCRIPTION OF THE INVENTION

[0020] It is to be understood that the figures and descriptions of thepresent invention have been simplified to illustrate elements that arerelevant for a clear understanding of the present invention, whileeliminating, for purposes of clarity, other elements. Those of ordinaryskill in the art will recognize that other elements may be desirable inorder to implement a particular embodiment of the present invention.However, because such elements are well known in the art, and becausethey do not facilitate a better understanding of the present invention,a discussion of such elements is not provided herein.

[0021]FIG. 1 is a side plan view of a device 10 constructed inaccordance with the present invention. The device 10 includes a writinginstrument 12 and a writing surface position indicator 14. The writinginstrument 12 may be a writing device such as, for example, a pen, amechanical pencil, a marker, and chalk. The writing instrument 12includes a housing 15 and a writing tip 16 connected to the housing 15to enable a user of the device 10 to place marks on a surface byapplying the writing tip 16 to any surface.

[0022] The writing surface position indicator 14 provides informationindicative of the relative position of the writing tip 16 to the surfaceon which the user is using the writing instrument 12. The writingsurface position indicator 14 communicates with the writing instrument12 to better determine the position of the writing tip 16 relative tothe writing surface. The communication between the writing surfaceposition indicator 14 and the writing instrument 12 helps the device 10track the marks being applied to the writing surface, even if thesurface is translated or rotated during use. The device 10 may trackmovement of the writing instrument 12 with a number of accelerometers36, and periodically correct the perceived position of the writinginstrument 12 with the writing surface position indicator 14, asdiscussed hereinbelow. Alternatively, the writing surface positionindicator 14 may be used alone to determine position and movement of thewriting instrument 12. To communicate the relative position of thewriting tip 16 to the surface, the writing surface position indicator 14is affixed to or engaged with the writing surface and transmits a signalto one or more sensors 17 in the housing 15. For example, the writingsurface position indicator 14 may be a clip fastenable to an edge orcorner of a writing surface. When the writing surface position indicator14 is not being used to provide information indicative of the relativeposition of the writing tip 16 to the writing surface, it may befastened to the writing instrument 12. For example, the writing surfaceposition indicator 14 may be fastened to an end of the writinginstrument 12 opposite the writing tip 16, such as is illustrated inFIG. 1. Further, the writing surface position indicator 14 may befastened to the end of the writing instrument 12 to protect the writingtip 16 when the device 10 is not in use.

[0023] In one embodiment, the writing surface position indicator 14 maybe a clip, such as on a clipboard, for holding the writing surface. Inanother embodiment, the writing surface position indicator 14 may be,for example, a sticker fastenable to the writing surface. In anotherembodiment, the writing surface position indicator 14 may be placed onthe writing surface and have sufficient mass, such as a paper weight, tomaintain a constant position relative to the writing surface even if thewriting surface is translated or rotated during writing.

[0024] In addition, the writing surface position indicator 14 may beactive or passive. For example, the writing surface position indicator14 may include a number of transmitters 18 to transmit a signal to thesensor 17 in the writing instrument 12. The device 10 determines therelative position of the writing tip 16 based on the received signal, asfurther described hereinbelow. Alternatively, the writing surfaceposition indicator 14 may be passive, such as by utilizing magneticcomponents. For example, the writing surface position indicator 14 maybe a magnetic substance, such as magnetic ink applied to the surface ora magnetic sticker fixably placed on the writing surface. In anembodiment in which the writing surface position indicator 14 ispassive, the sensor 17 detects the position and orientation of thewriting surface position indicator 14, such as by sensing a magneticfield generated by the writing surface position indicator 14, todetermine the relative position of the writing tip 16.

[0025] The device 10 may also include one or more other features tofacilitate its use. For example, the device 10 may include an input 19,such as a push button, to allow the user to select from various modes ofoperation and functions to be performed by the device 10, as furtherdescribed hereinbelow. The device 10 may also include a display 20, suchas a liquid crystal display, for providing a user with visualinformation, including information regarding user input (feedback). Thedisplay 20 may also, for example, serially display received and sentinformation, such as e-mail messages. In addition, a facsimile messagemay be received by the device 10, for example, by converting thefacsimile message into electronic form and displaying it on the display20, much like an e-mail message.

[0026] The device 10 may further include an audio interface system 21,including a speaker 22 and a microphone 24. The audio interface 21 maybe detachably connectable to the housing 15. When the audio interface 21is connected to the housing 15, it may allow the device 10 to provideconventional telephony communications using, for example, cellulartechnology contained within the housing 15, as discussed hereinbelow. Inaddition, the device 10 may, for example, be programmed to record audiodictation, to translate audio input into text to send via e-mail, or toconvert the text of a received e-mail message into audio output. Also,the audio interface system 21 may provide an audio signal when an e-mailmessage is received by the device 10.

[0027]FIG. 2 is a block diagram illustrating one embodiment of thedevice 10 including a processor 30. The processor 30 may be any one ofmany processors, such as one of the Pentium® family of processorsmanufactured by Intel Corp., Santa Clara, Calif. A memory device 32 iscoupled to the processor 30, and may be used to store instructions forthe operation of the device 10, as well as to store data collected bythe device 10. The memory device 32 may be, for example, 10 Mbytes ofsolid state memory. The memory device 32 may be volatile ornon-volatile. The memory device 32 may include ROM for storinginstructions to be executed by the processor 30. The memory device 32may include RAM, such as dynamic RAM or static RAM, for storinginstructions and data. The memory device 32 may be or include an EPROMfor storing instructions and data.

[0028] The device 10 may track the movement of the writing tip 16relative to the writing surface with the writing surface positionindicator 14 in conjunction with the pressure sensor 34 andaccelerometers 36. For example, one pressure sensor 34 may be connectedto and located near the writing tip 16 of the writing instrument 12.Alternatively, the pressure sensor 34 may be located along or at the endof a shaft 38 connected to the writing tip 16. The pressure sensor 34allows the device 10 to determine when the writing tip 16 is against awriting surface and the force with which the writing tip 16 is beingapplied to the writing surface, thereby allowing the device 10 todetermine when the user is writing as well as the fineness or thicknessof a line being drawn. The pressure sensor 34 may be, for example, astrain gauge based force sensor.

[0029] Movement of the writing instrument 12 may be determined from theaccelerometers 36, which may be connected to the shaft 38. Eachaccelerometers 36 may be, for example, a dual axis,micro-electromechanical accelerometer. Three accelerometers 36 may beused, as illustrated in FIG. 1, so that collectively they provide dataindicative of motion, including speed and direction, of the writinginstrument 12 in all three planes of three dimensional space. In analternative embodiment, three additional accelerometers 36 may beemployed to provide data indicative of roll, pitch, and yaw. Informationrelating to roll, pitch, and yaw of the writing instrument 12 during thewriting operation may provide for better handwriting recognition becauseinformation relating to rotation of the writing instrument 12 about aparticular point is obtained. Alternatively, the present invention mayonly utilize two accelerometers 36 to determine movement on the writingsurface, and the pressure sensor 34 alone is used to determine when thewriting instrument 12 is engaging the writing surface.

[0030] Used in conjunction with the pressure sensor 34 andaccelerometers 36, the writing surface position indicator 14 facilitatesdetermining the position of the writing tip 16 relative to the writingsurface, even if the writing surface moves during use, such as is oftenthe case during writing. Furthermore, the writing surface positionindicator 14 may be used by the device 10 to periodically calibrate theposition of the writing tip 16 relative to surface as determined by theaccelerometers 36 to compensate for the error in the position determinedthereby, which typically accumulates over time.

[0031] In an alternative embodiment, the writing surface positionindicator 14 may alone be used to track the movement of the writinginstrument 12. In that embodiment, the writing surface positionindicator 14 continually determines the position of the writing tip 16relative to the writing surface in three dimensions, thus enabling thedevice 10 to determine when the writing tip 16 is in contact with thesurface, and the movement of the writing tip 16 as it is applied to thesurface. The writing surface position indicator 14 communicates theinformation to the writing instrument 12 as described hereinbelow.

[0032] The memory device 32 may be programmed with instructions whichwhen executed by the processor 30 cause the processor 30 to recognizehandwriting using conventional handwriting recognition algorithms. Thememory device 32 may also be programmed to cause the processor 30 torecord in the memory device 32 non-recognized writings, such as drawingsand doodles written by the user.

[0033] A communication system 40 may also be provided so that the device10 may engage in external communication. For example, cellulartelecommunication technology, such as PCS digital cellular technology,may be contained in the writing instrument 12, and used to allow thedevice 10 to send and receive information. The communication system 40may be used, for example, to allow a user to use the device 10 as atelephone, with the aid of the audio interface system 21. Thecommunication system 40 may also allow a user to connect to theInternet, via an internal modem and Internet connection (not shown), sothat the device 10 may, for example, receive and send e-mail.

[0034]FIG. 3 is a top plan view of the device 10 being used to write ona piece of paper 42. The writing instrument 12 may be used to write onthe paper 42 in a conventional manner by applying the writing tip 16 tothe paper 42. In the embodiment of the present invention illustrated inFIG. 3, the writing surface position indicator 14 is a clip fastenableto an edge of the paper 42. According to that embodiment, the writingsurface position indicator 14 may be removed from the writing instrument12 and clipped, or otherwise fastened, to the paper 42. An embodiment ofthe writing surface position indicator 14 includes its own power supply,such as a rechargeable Lithium-ion solid polymer or liquid gel battery.The writing surface position indicator 14 may communicate one or moresignals that are used by the device 10 to determine the relativeposition of the writing tip 16. The signals may be, for example,infrared signals, ultrasonic signals, or electromagnetic signals. Thesignals from the writing surface position indicator 14 are received bythe sensor 17, which may be, for example, a receiver as through part ofthe communication system 40 (illustrated in FIG. 2).

[0035] The device 10 may use the signals communicated by the writingsurface position indicator 14 in any of several ways. For example, thesignals from the writing surface position indicator 14 may be used toprovide a reference for the device 10 of the relative position betweenthe writing tip 16 and the writing surface because the writing surfaceposition indicator 14 maintains a constant position relative to thepaper 42. As a result, even if the paper 42 is moved during use, asalmost always happens during writing, the device 10 will be able tomaintain its position relative to the paper 42, allowing the device 10to maintain an accurate record of what is being written. The writingsurface position indicator 14 also allows for periodic calibration ofthe device 10. For example, by maintaining a known reference point,established at the beginning of a writing session, the writing surfaceposition indicator 14 helps the device 10 compensate for small errors inits accelerometers 36 that accumulate over time. Without this feature,the movements recorded and used by the device 10 may become unusablynoisy within a few minutes of use.

[0036] In one embodiment of the present invention, the writing surfaceposition indicator 14 has two signal transmitters 18 separated by asmall distance. The writing surface position indicator 14 periodicallytransmits signals from the two transmitters 18 which are received by thesensor 17 The signals may be transmitted at different frequencies sothat they may be distinguished. The device 10 determines the exactposition of the writing instrument 12 relative to the writing surfaceposition indicator 14 by, for example, triangulation. The device 10 thenresets the internal value of where the writing instrument 12 is relativeto the surface (having over the past small fraction of a second beenapproximated by the accelerometers 36) to the value calculated based onthe information provided by the writing surface position indicator 14.In this way, “creep” can be avoided. The frequency of signalstransmitted by the writing surface position indicator 14 may varydepending on the accuracy required for a specific application and theaccuracy of the accelerometers 36. Furthermore, the device 10 canmaintain the position of the writing tip 16 relative to the paper 42even if the paper 42 is rotated, or otherwise moved, during the writing.In an alternative embodiment, the writing surface position indicator 14may produce a single signal from one transmitter 18, and the device 10may sense that signal with two spaced apart sensors 17 on the writinginstrument 12 (as illustrated in FIG. 1), so that the position of thewriting tip 16 relative to the writing surface position indicator 14 maybe determined using, for example, triangulation.

[0037] The device 10 may operate in several modes. The different modesmay be selected with the input 19. For example, the device 10 mayinclude an operation mode, a command mode, and an off mode. To operatein the different modes, instructions are stored in the memory device 32which when executed by the processor 30 cause the processor 30 tooperate the device 10 in the various modes. For example, the device 10in the operation mode monitors and records what is being written ordrawn by the user on the writing surface. The device 10 can beprogrammed to recognize the writing using handwriting recognitionalgorithms stored in the memory device 32.

[0038] In the command mode, the device 10 monitors the writing of theuser and interprets that writing as commands. For example, the user maysend previous writings and drawings, such as those monitored and storedin operation mode, by writing “send” followed by parameters for sending.For example, by writing “send 555-1234”, the device 10 will send thedata via facsimile. In contrast, if “send” is followed by an e-mailaddress, the data will be sent via e-mail. Of course, separate commands,such as “fax” and “e-mail,” may be used to avoid confusion. An “end”command, or any other command defined by the user, may be used toinitiate action by the device. For example, the symbol “->” may be usedto end and execute the command. The device may also use other commands,such as “save”, “read”, “contact”, “download”, and “phone”.

[0039] In “off” mode, the device 10 operates as a conventional writingdevice and does not perform other functions, such as handwritingrecognition.

[0040] The device 10 may also be used to define a personal interface.The interface may be used, for example, to enter data into the device 10or instruct the device 10 to execute specified commands. The interfacemay be defined by the user as a template including, for example, icons,words, and symbols on a surface, which are drawn with the device 10. Forexample, the user may enter command mode, write the word “interface”,and draw a template of numbers and functions that define a calculator,as illustrated in FIG. 4. The handwriting recognition feature of thedevice 10 allows it to recognize the numbers and letters, and the device10 can determine the writing tip's 16 position relative to those drawnnumbers and functions. To better define the personal interface, eachelement, such as each number 44 and each function 46 may be surroundedby a circle or box 48 to more clearly define a command area 50 so that,for example, touching the writing tip 16 inside the command area 50invokes that element or function, and touching the writing tip 16outside of the command area 50 does not invoke it. The user may touchthe writing tip 16 of the writing instrument 12 to the command area 50,and the device 10 will perform the command indicated by the user. Forexample, the user may draw a calculator then interact with the drawninterface as though it were a physical calculator. Answers may beprovided on the display 20. As a result, a user may balance theircheckbook on a piece of scrap paper while waiting at a bus stop. Whenfinished, the user may throw away or recycle the paper.

[0041] Other, potentially limitless, interfaces may also be created. Forexample, the template may be a keyboard, with the keys arranged in anyorder desired by the user, and the user may interact with the keyboardwith the writing tip 16 of the writing instrument 12. The entries madeby the user may be shown on the display 20, and the user may review theresults by drawing on the paper 42 up and down arrows, and then touchingthe arrows.

[0042] Also, the interface may be a user-defined macroinstruction. Forexample, as illustrated in FIG. 5, the user could write the name of aperson on the paper and circle it to define a command area 50, andinstruct the device 10 that whenever the user touches the writing tip 16to the command area 50 the device 10 is to transmit stored data to theperson's e-mail address. Moreover, the macroinstruction may be stored inthe memory device 32 of the device 10, such that it is saved, and willbe recognized by the device 10 without the user having to re-define theinterface during each subsequent use of the device 10.

[0043] Another example of an interface is that the user could write onthe paper 42 “FONT=COURIER,” circle it, and instruct the device 10 thatwhenever the user touches the writing tip 16 to the paper 42 within thecircle, the device 10 is to convert information stored in the memorydevice into ASCII text in courier font.

[0044] The various modes may also be used in conjunction. For example, auser could select the operate mode using the input 19, and then write ona piece of paper. In the operate mode, the device 10 recognizes thewriting, as described hereinbefore. Also, the user could instruct thedevice 10 to store the writing in the memory device 32 under aparticular index or file. Alternatively, in the command mode, the usercould instruct the device 10 to perform a macroinstruction saved as auser-defined interface, such as to e-mail the writing to a particularaddress.

[0045]FIG. 6 is a side plan view of the device 10 in a base 54. The base54 may be used to download data from the device 10 and transmit it to aremote device, such as a personal computer. The base 54 may also chargethe power supplies of the device 10. The power supplies for the device10 may be, for example, an internal rechargeable Lithium-ion solidpolymer or liquid gel battery. In addition, the base 54 may be utilizedto upload instructions into the memory device 32 of the device 10. Acord 56 on the base 54 may be used to connect the device 10 to a remotedevice, such as to a computer and/or to a power supply. Alternatively,the base 54 could be wireless.

[0046] The present invention also includes a method of operating thepresent invention. The method includes defining and using a personalinterface. The interface may be defined with a pen, as describedhereinbefore, or it may be defined in other ways. For example, asillustrated in FIG. 7, the invention may be embodied as a ring or sleevethat fits on a user's finger. The writing instrument 12, for example,may be a ring with an extension 60 that engages the paper 42 and housesa pressure sensor 34. A writing surface position indicator 14 may beremovably attached to the writing instrument 12 and attached to paper 42when writing. In that way, the user may write and draw with the fingeras if it were the device 10 described hereinbefore. Feedback may beprovided to the user by a display 20 mounted on the ring.

[0047] Those of ordinary skill in the art will recognize that manymodifications and variations of the present invention may beimplemented. For example, a user need not define an interface on awriting surface, but could instead define an interface in space, such asby moving the writing instrument 12 similar to waving a baton. A usercould distinguish to the device 10 when he is defining the interface andinteracting with it from merely moving the writing instrument 12 frompoint to point, such as by indicating so to the writing instrument 12 bydepressing the input 19. The foregoing description and the followingclaims are intended to cover all such modifications and variations.

What is claimed is:
 1. A device, comprising: a housing; a writing tipconnected to the housing; a writing surface position indicator; aprocessor in the housing; a memory device in the housing connected tothe processor; and a sensor in the housing and cooperative with thewriting surface position indicator.
 2. The device of claim 1, whereinthe writing surface position indicator is removably fastenable to awriting surface.
 3. The device of claim 1, further comprising aplurality of accelerometers connected to the writing tip.
 4. The deviceof claim 3, further comprising a pressure sensor connected to thewriting tip.
 5. The device of claim 1, wherein the writing surfaceposition indicator includes a signal transmitter.
 6. The device of claim5, wherein the sensor includes a signal receiver.
 7. The device of claim6, wherein the sensor includes a second signal receiver.
 8. The deviceof claim 6, wherein the writing surface position indicator includes asecond signal transmitter.
 9. The device of claim 5, wherein the writingsurface position indicator includes a signal transmitter selected fromthe group consisting of a active signal transmitter and a passive signaltransmitter.
 10. The device of claim 5, wherein the writing surfaceposition indicator includes a signal transmitter selected from the groupconsisting of an infrared signal transmitter, an ultrasonic signaltransmitter, and an electromagnetic signal transmitter.
 11. The deviceof claim 1, wherein the memory device includes instructions storedthereon which when executed by the processor cause the processor todetermine relative position between the writing tip and a writingsurface.
 12. The device of claim 11, wherein: the sensor periodicallyreceives a signal from the writing surface position indicator; and thememory device includes instructions which when executed by the processorcause the processor to periodically update the relative position betweenthe writing tip and the writing surface.
 13. The device of claim 1,wherein the memory device includes instructions which when executed bythe processor cause the processor to recognize data written with thewriting tip on a writing surface.
 14. The device of claim 13, whereinthe memory device includes instructions which when executed by theprocessor cause the processor to execute commands in response to therecognized data.
 15. The device of claim 13, wherein the memory deviceincludes instructions which when executed by the processor cause theprocessor to recognize a user-defined interface defined by therecognized data.
 16. The device of claim 1, further comprising a baseconnected to the housing.
 17. A device, comprising: a housing; a writingtip connected to the housing; a writing surface position indicator; aplurality of accelerometers connected to the housing; a pressure sensorconnected to the writing tip; a processor in the housing; a memorydevice in the housing connected to the processor; and a sensor in thehousing and cooperative with the writing surface position indicator. 18.A device, comprising: a housing; a writing tip connected to the housing;means for providing a signal indicative of a writing surface; a sensorconnected to the housing for receiving the signal.
 19. The device ofclaim 18, further comprising means for determining the relative positionof the writing tip to the writing surface.
 20. The device of claim 19,further comprising means for tracking the relative position of thewriting tip to the writing surface.
 21. The device of claim 20, furthercomprising means for recognizing data written on the writing surface inresponse to the means for tracking.
 22. A device, comprising: a housing;a writing tip connected to the housing; a processor in the housing; amemory device in the housing connected to the processor and havingstored thereon instructions which when executed by the processor causethe processor to recognize an interface defined by writing on a writingsurface.
 23. The device of claim 22, wherein the memory device includesinstructions which when executed by the processor cause the processor torecognize user interaction with the interface.
 24. The device of claim23, wherein the memory device includes instructions which when executedby the processor cause the processor to execute commands based on therecognized interaction.
 25. A method for determining a relative positionbetween a writing instrument and a writing surface, comprising:producing a signal at a fixed location relative to the writing surface;receiving the signal at the writing instrument; determining the relativeposition of the writing instrument relative to the fixed location. 26.The method of claim 25, wherein producing a signal is selected from thegroup consisting of producing an infrared signal, producing anultrasonic signal, and producing an electromagnetic signal.
 27. Themethod of claim 25, wherein producing a signal is selected from thegroup consisting of producing an active signal and producing a passivesignal.
 28. The method of claim 25, wherein determining the relativeposition includes determining the relative position by triangulation.29. The method of claim 25, further comprising producing a second signalfrom a second fixed location relative to the surface, wherein the fixedlocation and the second fixed location are spaced apart by a distance.30. A method of tracking relative movement between a writing instrumentand a writing surface, comprising: determining movement of the writinginstrument; periodically producing a signal from a fixed locationrelative to the writing surface; receiving the signal at the writinginstrument; and updating a position of the writing instrument relativeto the writing surface.
 31. A method for defining an interface,comprising: monitoring movement of a writing instrument on a writingsurface; recognizing a command area on the writing surface defined bymovement of the writing instrument; associating a command with thecommand area; and determining whether the writing instrument touches thewriting surface within the command area.
 32. The method of claim 31,further comprising executing the command if the writing instrumenttouches the writing surface within the command area.
 33. The method ofclaim 32, wherein monitoring movement of the writing instrumentincludes: periodically producing a signal from a fixed location relativeto the writing surface; receiving the signal at the writing instrument;and updating a position of the writing instrument relative to the fixedlocation.